In large heavy cooking pan, add butter and oil. Then add chopped onion and garlic as butter melts. Saute onion and garlic for approximately 5 minutes, until tender.

Add sweet potatoes and carrots to onion and garlic mixture. Saute all ingredients together on medium heat for an additional 5 minutes.

Add chicken broth, and cumin with other ingredients in large pan. Bring mixture to a full boil and then reduce heat to simmer and cover pan, cooking for 30 to 35 minutes or until vegetables are tender and well cooked.

Using a food processor or a blender or an immersion blender, puree all ingredients until smooth and creamy. Add milk or milk of choice such as low-fat or half and half. Season to taste with salt and pepper.